This is a major rework of how we represent, handle, and render splits in
the macOS app.
This new PR moves the split structure into a dedicated, generic
(non-Ghostty-specific) value-type called `SplitTree<V>`. All logic
associated with splits (new split, close split, move split, etc.) is now
handled by notifications on `BaseTerminalController`. The view hierarchy
is still SwiftUI but it has no logic associated with it anymore and
purely renders a static tree of splits.
Previously, the split hierarchy was owned by AppKit in a type called
`SplitNode` (a recursive class that contained the tree structure). All
logic around creating, zooming, etc. splits was handled by notification
listeners directly within the SwiftUI hierarchy. SwiftUI managed a
significant amount of state and we heavily used bindings, publishers,
and more. The reasoning for this is mostly historical: splits date back
to when Ghostty tried to go all-in on SwiftUI. Since then, we've taken a
more balanced approach of SwiftUI for views and AppKit for data and
business logic, and this has proven a lot more maintainable.
## Spatial Navigation
Previously, focus moving was handled by traversing the tree structure.
This led to some awkward behaviors. See:
https://github.com/ghostty-org/ghostty/issues/524#issuecomment-2668396095
In this PR, we now handle focus moving spatially. This means that move
"left" means moving to the visually left split (from the top-left
corner, a future improvement would be to do it from the cursor
position).
Concretely, given the following split structure:
```
+----------+-----+
| | b |
| | |
| a +-----+
| | |
| | |
| | |
| | |
|----------| d |
| c | |
| | |
+----------+-----+
```
Moving "right" from `c` now moves to `d`. Previously, it would go to
`b`. On Linux, it still goes to `b`.
## Value Types
One of the major architectural shifts is moving **purely to immutable
value types.** Whenever a split property changes such as a new split,
the ratio between splits, zoomed state, etc. we _create an entirely new
`SplitTree` value_ and replace it along the entire view hierarchy. This
is in some ways wasteful, but split hierarchies are relatively small
(even the largest I've seen in practical use are dozens of splits, which
is small for a computer). And using value types lets us get rid of a ton
of change notification soup around the SwiftUI hierarchy. We can rely on
reference counting to properly clean up our closed views.
> [!NOTE]
>
> As an aside, I think value types are going to make it a lot easier in
the future to implement features like "undo close." We can just keep a
trailing list of surface tree states and just restore them. This PR
doesn't do anything like that, but it's now possible.
## SwiftUI Simplicity
Our SwiftUI view hierarchy is dramatically simplified. See the
difference in `TerminalSplitTreeView` (new) vs `TerminalSplit` (old).
There's so much less logic in our new views (almost none!). All of it is
in the AppKit layer which is just way nicer.
## AI Notes
This PR was heavily written by AI. I reviewed every line of code that
was rewritten, and I did manually rewrite at every step of the way in
minor ways. But it was very much written in concert. Each commit usually
started as an AI agent writing the whole commit, then nudging to get
cleaned up in the right way.
One thing I found in this task was that until the last commit, I kept
the entire previous implementation around and compiling. The agent
having access to a previous working version of code during a refactor
made the code it produced as follow up in the new architecture
significantly better, despite the new architecture having major
fundamental differences in how it works!
Conversion of #7497 to a PR. This implements a feature requested in
#7331: an option to hide the default window buttons on macOS for a
cleaner aesthetic.
~~Builds on #7502 as it requires the same change to avoid the main
toolbar title showing on top of the tab bar.~~ EDIT: rebased on main now
that #7502 was merged.
I aligned the scope of the new option with `macos-titlebar-style`, since
they both customize titlebar elements. This means it has the same edge
case quirks: For example, if you change the setting, reload the config,
and then open a new tab, the appearance of the current window will
depend on which tab is in the foreground. I did it this way because
`macos-titlebar-style` provided an easy template for which derived
configs and functions to modify. Let me know if you want me to try
adjusting this so that a change in the setting also takes effect for
current windows/tabs, which I _think_ should be possible.
Screenshots:
* `macos-titlebar-style = transparent` (default)
* `macos-titlebar-style = tabs`
This fixes a small memory leak I found where the `SplitNode.Leaf` was
not being deinitialized properly when closing a split. It would get
deinitialized the next time a split was made or the window was closed,
so the leak wasn't big. The surface view underneath the split was also
properly deinitialized because we forced it, so again, the leak was
quite small.
But conceptually this is a big problem, because when we change the
surface tree we expect the deinit chain to propagate properly through
the whole thing, _including_ to the SurfaceView.
This fixes that by removing the `id(node)` call. I don't find this to be
necessary anymore. I don't know when that happened but we've changed
quite a lot in our split system since it was introduced. I'm also not
100% sure why the `id(node)` was causing a strong reference to begin
with... which bothers me a bit.
AI note: While I manually hunted this down, I started up Claude Code and
Codex in separate tabs to also hunt for the memory leak. They both
failed to find it and offered solutions that didn't work.
Fixes#7236
Supersedes #7249
This removes all of our `focusedValue`-based tracking of the surface
title and moves it completely to the window controller. The window
controller now sets up event listeners (via Combine) when the focused
surface changes and updates the window title accordingly.
There is some complicated logic here to handle when we lose focus to
something other than a surface. In this case, we want our title to be
the last focused surface so long as it exists.
Fixes#6999
It appears that at some point one of the operations causes focus to move
away for non-native fullscreen. We previously relied on the delegate
method to restore this but a better approach appears to handle this
directly in the fullscreen implementations. This fixes the linked issue.
I still think long term all the `Ghostty.moveFocus` stuff is a code
smell and we should be auditing all that code to see if we can
eliminate it. But this is a step in the right direction, and removes one
of those uses.
This replaces the use of our custom `Ghostty.KeyEquivalent` with
the SwiftUI `KeyboardShortcut` type. This is a more standard way to
represent keyboard shortcuts and lets us more tightly integrate with
SwiftUI/AppKit when necessary over our custom type.
Note that not all Ghostty triggers can be represented as
KeyboardShortcut values because macOS itself does not support
binding keys such as function keys (e.g. F1-F12) to KeyboardShortcuts.
This isn't an issue since all input also passes through a lower level
libghostty API which can handle all key events, we just can't show these
keyboard shortcuts on things like the menu bar. This was already true
before this commit.
